Preparation of olefine derivatives



Jan. 27,1931. H. s. DA'vls ETAL PREPARTION OF OLEFINE DERIVATIVES Filed Feb. 24, 192s Patented Jan. 27, 1931 UNITED STATESf PATENT OFFICE` HAROLD S. DAVIS, OF BELMONT, AND WALLACE J'. MURRAY, OF READING, MASSE CHUSETTS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO PETROLEUM CHEMICAL COR- PORATION, F NEW YORK, N. Y., A CORPORATION OF DELAWARE PREPARATION OF OLEFINE DERIVATIVES Application led February 24, 1925. Serial No. 10,992.

This invention relates to the preparation, segregation and utilization of olefine hydrocarbons and to the production of their derivatives, including alcohols and other useful substances. The olenes may be derived from `such materials as petroleum, peat, coal, oil shales, and like carboniferous natural materials by cracking or pyrogenesis, so called.

The olefine mixtures produced by heating such substances to temperatures resulting in pyrogenetic transformations are, as is well known, exceedingly complex, generally containing ethylene, propylene, butylenes, amylenes, hexylenes and higher oleiines of the general formula CDHQD. Unlike saturated hydrocarbons, olefines are capable of readi ly reacting or combining with reagents, including the polybasic acids (of which sulfuric acid or phosphoric acid are typical) the halogens and halogen compounds, hypochlorous and other acids.

The reaction of sulfuric acid with the olenes has been known since its discovery in Faradays laboratory in 1826, and alcohols have been prepared from alkyl sulfuric acid products of this reaclion on certain olefines by hydrolysis and distillation bynumerous investigators since Berthelots research in 1863. Derivatives of olefines have been made on a commercial scale in this country by first preparing an acid reactive liquor of sulfuric acid with oil as since as early as 1906 (American Ether mpany of Richmond, Virginia; P. Fritzsche, Zeitschrift fur angewandte Chemie, 1896, pp. 456, 459; Die Chemische Industrie, vol. 35, p. 637, 1912). Gases produced in the liquid phase cracking of petroleum have been simmixtures including isopropyl, secondary butyl and amyl alcohols. These treatments, so far as We are aware, have been approprate to the incidental recovery at gas works or petroleum pressure stills of gases from ilarly treated for the recovery of alcoholic' cracking operations rarely containing more than 12% of olenes, and free from any substantial contents of very reactive highly cracked hydrocarbons such as the diolefines.

'When any attempt has been made to produce industrially from mixed oleine bearing gases, such as the waste gases from liquid phase cracking, acid reactive liquors capable of hydrolysis and distillation to obtain alcohols, sulfation has been carried out, so far as we are aware, by reaction upon the whole gaseous mixture with acid of a degree of concentration selected to reach a result necessarily in the nature of a compromise between destruction by polymerization or otherwise of the more reactive oleines, and incomplete sulfation; and hence, with partial recovery only of the realizable oleline values and with high acid consumption. Such processes are economically justifiable only when lean gases are available in great quantities otherwise wasted. They are not so justifiable when the gas to be treated is rich in olefines so reactive as to be converted into polymers while making the olefine-acid compound of a less reactive remainder. When the olefine bearing gas is rich in highly reactive ole'ines, a single-stage treatment to obtain acid products can not be practised; the reaction of the more highly reactive olefines and other hydrocarbons to pol mer under treatment with acids capable of fbrming addition compounds with the less reactive olefines is too vigorous and too productive of heat to permit this even in the case of relatively lean gases. The procedure has been to destroy the very reactable olenes in one lot of acid, and sulfate the remainder in another lot of acid.

If it were practicable to obtain mixed alkyl acid compounds and other derivatives of the rich ases, such as result from vapor phase crackmg directed to the production o olenes, by a grou reaction with acid, the result would not desirable. The different alcohols, at least ei ht in number, resulting from hydrolysis of t e obtainable compounds have boiling points ranging from 80 to 140 C., and se aration from each other is in most cases not easible. The uses of these alcohols (e. g. isopropyl and amyl alcohols) are widely divergent, and to produce them in admixture would be commercially undesirable.

This process provides a treatment of olefine hydrocarbons, liquid or gaseous, particularly'mixed hydrocarbons resulting from as complete generation of these substances as possible from asuitablehydrocarbon material or carboniferous material of the classes above enumerated, and therefore occurring richly in the material presented for treatment, and containing the very reactive highly cracked hydrocarbons such as the dioleines, isobutylene, trimethylethylene, unsymmetrical methyl-ethyl-ethylene, and other unsaturated bodies having a high reactive aiinity for combining acids or other reactants, and also containing other olefines of a lower order of reactivity toward the said combining agents; for example propylene, isopropyl, ethylene, butene-l, butene-2, pentene-l an,d pentene-2. *i

This invention has for one of its objects to provide a mode of treatment applicable to hydrocarbon products rich in highly reactive or unsaturated olefines to recover valuable derivatives and to segregate the olefine substances in the order of their chemical activities toward reagent substances, for example polybasic acids; and which will permit the separate production, severally or in groups, of olefine compounds, such as the oleine-acid compounds capable of hydrolysis or other after-treatment and separation, leading to separate production of the consequent alcohols or other olefine derivatives. An object attained by the process is the separation of different complex olefine mixtures, especially mixtures rich in olefines. into fractions substantially according to the order of the molecular weights of their principal contents,

and the treatment severally of these fractions of the optimum production of valuable derivatives, e. g. the appropriate alcohols, in a relatively pure and unmixed state; and without substantial destruction at any stage of this separation of any of the several fractions at the respective stage of the operations.

The process conserves for use at a further stage of the process such of the reactive olefines as are not concerned at any stage of the process in the' reaction contrived and intended to produce a particular derivative or intermediate. The recommended procedure comprises a stage or stages of separation of a fraction or fractions of the material containing the olene or oleine group to be recovered, followed by treatment selectively to differentiate and segregate the component olefine substances in accordance with their reprocess, to proceed upon a basis of known contents of the raw material, and for this purpose a preferred raw material for the rocess is petroleum, treated by any process o vapor phase cracking tending to produce a product rich in olefines and preferably substantially free from normally liquid paraliine derivatives. A suitable and preferred raw material is the constant and controllable mixture produced by the process described in the aplication for Letters Patent by Earl P.

tevenson and Clarence K. Reiman, Serial No. 8,907, filed February 13, 1925, which comprises subjecting vapors of a petroleum or a fractional distillate of petroleum, for example' gas oil, so called, to heat during flow in a tubular retort heated at successive zones thereof to differing degrees, with the eli'ect of. maintaining the vapors at a nearly constant crackin temperature during a substantial time of ow, this constant temperature being such as to result in optimum development of olefine values. For this purpose, a cracking temperature maintained nearl constant at a selected value between 600 and 650 C. during a sutiicient time of flow to produce from 1000 to 1700 cubic feet of gaseous product per barrel of 42 Gallons passed produces satisfactory materlal for this treatment. The preferred vapor-phase cracking temperatures are higher than those heretofore known for the commercial production of motor spirit, which do not exceed 500 C., 1

so far as I am aware (Lewes, Journal Society of Chemical Industry, Vol. XI, page 585) and are not such high temperatures (700 to 1000 C.) as are used for making oil gas by the known methods of Pintsch, Fritsche or Ullmann.

The invention will therefore now be described as carried out upon the gaseous elux of vapor phase cracking of petroleum so contrived as to produce a vaporous and gaseous ailiux which, when stripped of a motor spirit fraction, is exceedingly rich in the olefine substances above mentioned. But it will be understood that this rocess is applicable without change, except 1n degree, to the treatment of other complex oleine mixtures, and that the specific instances now to be described are described by Way of illustration of the invention, and are not to be viewed as comprising every instance of practice according to the invention.

In the accompany drawing, the figure is a diagrammatic flow sheet showing a preferred sure device 3 the material is forced into a.

preheater or primary vaporizer 4 (preferably a suitable tubular coil) and through a superheater or secondary vaporizer 6, which may be substantially the same kind of tubular heater as the primary preheater 4. Between the preheater 4 and su erheater 6 the flowing stream, already su tantially all vapor, may be subjected to treatment adapted to separate out the inclusions of low volatility, and pass on the vapors and gases. A liquid separator 5, preferably of a kind operating without substantial loss of heat, is recommended. Collected liquids from this separator may flow through a pipe 6a and a coolerC to tar storage tanks 10.

Va ors superheated at 6 pass to a cracking tube The eiiluent gases, vapors and suspensions from cracking are recommended to e treated in a separator 8, which may work on the cyclonic or centrifugal principle, and deliver its liquid separates into the pipe 6, and its vaporous and gaseous eillux into the bottom of the first of a series of separating and condensing towers, for example, the tower 11, adapted to counter-current flow in contact of the vapors and gases'and the condensate from tower 12, which in turn is adapted to countercurrent flow of the vapors and gases and the condensate from a fractionating condenser 13 of any suitable reflux A type.

heavy and undesirable tars formed in the cracking reaction. From one of the lower plates of this tower is drawn off a fraction of substantially the same boiling range as the feed stock, but as this will, of necessity, contain some hydrocarbons in the motor spirit range, it can not be returned to the feed stock without materially decreasing the yield of motor spirit. Provision is included, therefore, for stripping this fraction of its lighter hydrocarbons, "such as a fractionating tower 12, which is heated at the base at 14 and delivers overhead the desired fraction of its feed into one of the top lates of tower 12. The stripped cycle stoc is delivered through a pipe 14'l and cooler C* to the feed stock tank. The overhead from 13 is cooled at 18, and the condensate at this point is crude motor spirit in the preferred operation of tower 12.

The vaporous effluent from condenser 18 is now fractionally condensed or absorbed, or otherwise treated to separate olefine fractions, which from their preponderant contents, may be described as an amylene fraction, a butylene fraction, and a gaseous fraction rich in propylene and ethlyene, and hereinafter referred to as a pro ylene fraction.

For example, the gaseous e uent from condenser 18 may be delivered through meter M and scrubbed in absorption towers 20 and 21 by a countercurrent flowv of cool absorption oil stored in a tank 23, delivered by a pump P through a cooler C2, and pipe 24 to the to of tower 21, to receiver 25, pum ed at 2 through a cooler C3 to the top o tower 20, and the saturated oil delivered through a pipe 26 to a storage tank 27, whence the saturated oil may How through a heat exchanger 28, pipe still 29 and vaporizer 30 to a refluxing tower 31, from which the liquids may be le'd through cooler C* to the crude motorspirit or gasoline storage tank 16 by pipe 32. Unvaporized absorption oil from va orizer 30 may liow through pipe 30, heat exc anger 28, and cooler C5 to tank 23.

The vaporous efiluent at 33 may be delivered through a condenser 34 and a separator 35, when ce the vapors pass to a compressor 36 and pressure storage tank 37. Condensates at 34, 35 and 37 may be delivered to tank 17, the pressures and temperatures being such as to provide at these points liquid fractions corresponding to the amylene-fraction fluid in tank 17. Pressure tank 37 may deliver, if desired, through a suitable reduction valve 39 to gas-holder 40, in which are collected the residual gases from the saturated scrubbing oil. This gaseous fraction, if so separated` represents substantially the major portion of the butylene hydrocarbons, whereas the residnal gas from tower 21, collected in the holder 22. contains the propylene and ethylene.

When appropriate conditions are realized in and prior to flow through the cracking tube 7, the respective fractions capable of being separated by steps of condensation or absorption are sharply characterized bythe desired preponderance (amounting under good conditions to substantial freedom from mixture with each other) of the olelne substances sought to be collected and separated. Any suitable condensation or absorption fractionating treatment may therefore be resorted to, and the apparatus mentioned may be varied in accordance with engineering preferences.

Under preferred conditions, cracking in the tube 7 is at a relatively constant temperature at or about 600 C. to 615 C.

lhe `following typical exam le of operation of the vapor hase crac 'ng process above described and) the segregation of the olefines into comparatively sim le fractions shows the relative amounts invo ved and the quantity of each fraction Results of .S2-hour mn (quantities per bbl. throughf out) l. Gas oil used. 31 Baume. 2. Crude motor-spirit recovered 74.5 lbs. 3. Cycle stock 110 lbs. 4. Fuel oil 30 lbs. 5. Process at M (rich gas) 80 lbs. (i040cu.{t.) 6. Residu gas from compression to 260 pounds per sq. in 33.4 lbs. (533 cu. it.) 7. Pressure condensate 40.61lbs.

Products from pressure condensate 8. Amylene fraction iquid):

g) Up to 25 9. Butylene fraction 10. Light naphtba (inc uded in 2)- 4.5i lbs. 5.15 lbS. 19.6 lbs. (181 cu. It.) 11.35 lbs.

Entrance 2 3 4 5 6 595 C. 692 602 C. 603 C. 606 C. 603 C.

Conversions per bbl. passed Process gas (sp. gr. 1.055) 1035 Cu. ft. Oil scrubbed gas (sp. gr. 0.929) 675 cu. ft. Butylene fraction (non-condensed as from distillation nf saturated absorpt on oils) (sp. giu-4.52) 102 cu. it. Amyiene fraction (condensbies recovered by fractionation to 60 C.) 2. 6 gallons Crude naphtha (condensibles between 60 and 210 C. 9. 3 gallons Cycle stock (condensibles above 210 C.).. 19 gallons Tar residues 2. 1 gallons Oleflne content of gaseous fractions Process gas per cent olefines above ethylene 33. 1 Oil scrubbed gas per cent olenes above eth lene 17.' 8

Butylene fraction per cent oleflnes above et ylene- 75. 7 Vapor phase cracking of the preferred practice having been carried on at the temperatures mentioned, the products are chiefly i urated or arailn hydrocarbons, particularly in the lig ter liquid fractions. The olene content of the gas prior to compressing or oil scrubbing to remove condensibles may be as high as 54% by volume in the operation of an appropriate vapor lphase cracking process, for example that described. For comparison, the olefine content of pressure-still gases is seldom higher than 10%, and is usually under 8%, justifying designation as lean gases.

Theaggregate chemical character of these two classes of olefine mixtures is likewise quite different, so that steps for the recovery of derivatives applicable to the lean gases are not applicable to the richer mixtures. The olefines in pressure-still gases have a high proportion of normal olenes, and do not contain substantial amounts of the very reactive, highly cracked hydrocarbons, such as the diolenes.

The recommended steps above described, for which other procedures may of course be substituted Within the invention so lon as the results are produced, result in a fractionation of the olefines as follows:

Boiling points- Ethylene 103 C. Propylene 48.4 C Gaseous Iso-butylene 6 C Butylenes Butene-i 5 C. Butene +1 C. isopropyl ethylene 21 C. Umsym. methyl-ethyi-ethyl- Am ienes me 31 33o C Liquid y Pantone-2 36 'ilrmethyl ethylene 37 to 42 C Pentene-l 39 to 40 C Hexylenes to 75 C Higher oleiines, up to 150 C.

Associated with the amylenes and butylenes are substantial inclusions of diolefines, believed to be butadiene, isoprene, and their homologues.

We are aware of no practical arrangement of conditions or procession of reagent substances by which any whole mixture of these gaseous substances can be treated to yield in succession the derivatives of the unsaturated hydrocarbons present in them in amounts constitutin valuable sources of materials needed for lndustrial uses. But we have nevertheless determined that the substances are reactive with the polybasic acids, for exam le sulfuric acid, in a certain' order, ethylene eing the least reactive, as follows:

amm una 1. Ethylene CH2=CH3 103 C. Gas 2. Propylene C H,CH=CH2 48.5 C. Gas 3. Paname-1 CH.-CH.-CH.-CH=CH, :ae-40 C. Liquid 4. Pentene-2 CH-CH2CH=CHCH, 36 C. (741 mm.) Liquid 5. Butene-l CH8-CH2CH=CH2 -5 C. Gas or. in solution 6. Butene-2 CHCH=CH-CH.l +1 C. Gas or. 1n solutlon 7. Isopropyl ethylene CH3 CH-CH=CH, 21.1 C. Llquld H3 8. Unsymmetrical methyl ethyl CH ethlene :CH2 31 to 33 C. Liquid CH3-CH,

9. Trimeth l eth lene CH CH y y f a c=o 37m 42 o. Liquid CH3 H 10. Iso-butylene CH i C=CH2 6C. Gas or 1n CH3 Y solution To absorb ethylene and produce ethyl sulfuric acid it is necessary to use hot concentrated acid which will substantially polymerize all other olefines above propylene in reactivity; the propyle-ne will also be polymerized.

With 100% acid below 30 C., there is no appreciable absorption of ethylene and the absorption of propylene is very rapid, but the yield of isopropyl alcohol will be small due to excessive polymerization when and if the gas treated contains the more reactive olefines in the amounts in which they naturally occur.

The following causes may be responsible for this phenomenon:

(l) The reactive olefines evolve s'o much heat on contact with the sulfuric acid that local overheatin occurs which tends to polymerize all the issolved products including propylene.

(2) The reactive olefines combine with the I sulfuric acid more rapidly than propylene and decrease the ability of the acid to absorb the latter.

(3) 100% sulfuric acid can easily act as an oxidizing agent toward the reactive olefines and the water evolved dilutes the acid and lowers its power to absorb olefines.

Per contra, if the gas is treated with acid of a strength adapted to absorb trimethyl ethylene and of the proper strength and under the optimum conditions to absorb the oleines which yield tertiary derivatives (Nos. 8, 9, l0 above) there is no substantial absorption of the lighter and simpler olefines such as propylene. For a quantitative idea of the great variations in reactivity manifested by these olefines towards sulfuric acid, isobutylcne is several hundred thousand times as reactive as ethylene.

In the case of isopropyl ethylene, which so far as we are aware has never, previous to the research leading to this invention, been converted into an alcohol throu h reaction nwith sulfuric acid, acids of suliicient strength to absorb pentene-l and pentene-2 quantitatively polymerize isopropyl ethylene at temperatures below 30 C. Higher temperatures and more concentrated acid than this are required to absorb the other olelines for -the results desired, and the conditions for securing a. good yield of amyl alcohol from this particular olefine substantially pol merize the other oleines except ethylene and'propylene present in this mixed gas.

By the fractionating procedure above described we have avoided any necessity to subject to sulfuric acid absor tion all of the re.

active olelines at once, an any necessity for producing alcohols incapable of being subsequently separated.

By processes extending and develo ing the results of this invention, some of w ich are the work of others and no part of this invention, at least eight different alcohols may be produced from the vapor-phase cracked hydrocarbons, having a boiling range extendin from to 140 C. A

f these were produced conjointly it would be impractical subsequently to separate them, and as the uses (of isoprop l and amyl alcohols, for example) are widely divergent, such a mixture would be of little or no commercial value. As a specific example of this diiculty two pairs of alcohols that can not be separated by fractional distillation are:

Isopropyl alcohol (constant boiling mixture)-boiling point 80.4 C.

range tiary as well as secondary derivatives call for a further departure from the art as practiced l where tertiary derivatives are not recovered. The usual procedure is to moderately dilute the product from sulfuric acid absorption with water and then distill. The point to which this dilution must be carried to avoid destruction by the action of the sulfuric acid on the alcohols during distillation varies with the different alcohols but in the case of secondary alcohols there is little hazard in distilling from 25% acid solution. Tertiary alcohols, however, behave quite diderently and tertiary amyl alcohol, for example, can not safely be distilled from even a one per cent solution without substantial decomposition. The preferred procedure for recovering tertiary alcohols from admixture with sulfuric acid is to neutralize as with lime and distill from a neutral solution. It will be obvious that this procedure is not practical when applied to a complex sulfuric acid product containing small percentagesof tertiary bodies as compared to secondary bodies. It becomes practical and feasible when the tertiary bodies are concentrated and segregated as in the practice of this invention.

The procedure above described, to avoid the difiiculties and provide the advantages just adverted to, separates the material into groups capable of being reacted upon preferentially in respect to their' constituent members,.thus enabling separations of the acid combinations with the constituent members of these groups 1severally. So far as there is advantage in `separating them, these groups are: *i

(1) The gaseous fraction containing ethyl*- ene and ropylene, i

(2) Tlrie butylene fraction containing isobutene and butene-1 or butene-2 or both of the initial low-boiling distillate fraction, and

(3) The residue of the condensate which may contain each of the live isomeric amylenes, with varying amounts of hexylenes and hi her olefines.

raction (1) may now be treated in accordance with the specific relative properties of its constituents. Because this fraction will contain traces of diolefines and olefines more reactive than propylene, owing to the practical and obvious limitation of any stem for physical fractionation, it is desira le to treat this fraction first with sulfuric acid, b tower scrubbing, of a strength that will se ectively react upon the olefines (more reactive than propylene) therein present.

In the preferred procedure this fraction is first scrubbed with acid of -8470 strength and is then subjected to the action of sulfuric acid having a concentration from 95 to 100% at a temperature preferably below 30 C., whereupon propylene is substantially absorbed. The ethylene remains relatively unaffected and may be preserved and used in the gaseous conditlon, or subsequently be reacted u on, as for example by absorption in hot sul uric acid resulting in the formation of ethyl sulfuric acid; or treated in any known way to produce ether. Specific and preferred modes of treating fraction (1) for the recovery of these values form no part of the present invention.

Gaseous products belonging to other series of hydrocarbons which may be present in minor quantities as impurities, either remain in the gaseous state, as in the case of methane or ethane, or remain unabsorbed by the acid treatments; or, as in the case of acetylenes, are converted into heavy compounds readily 'separable from the remainder, as by fractional distillation. If present, such bodies are not found in important quantities, and the resulting polymer isa heavy oily compound, of relatively uniform characteristics. In practice with hydrocarbon mixtures obtained as herein described the proportional amounts both of such extraneous gaseous products and of the heavy oily polymer resulting from acid treatment are relatively small.

Upon `hydrolysis of the acid compounds severally obtained as described, under suitable conditions, as by the addition of water or steam, and distilling at corresponding temperatures, ethyl and isopropyl alcohols respectively may be recovered in the distillates, leaving a residue of substantially alcoholfree sulfuric acid.

The butylene fraction (2) capable of economic use contains butylenes difficult to separate from each other by distillation. Of these butene-l and butene-2 are less reactive chemically than iso-butylene. Derivatives ofl c on c cb cm Preferred procedures therefore comprise reacting upon the butylene fraction in the order of reactivity of these component sub- 5 (all gaseous) is passed through sulfuric acid of a concentration of more or less in such manner as to effect as intimate a contact. between the gas and the acid as possible, for the purpose of absorbing iso-butene.

l0 Recommended apparatus comprises an interrupted flow tower with glass or other inert packing arranged for counter-current flow of gas and acid. Isobutene is very highly reactive; a satisfactory differential absorpof the cutter 18 and on a center 15 coaxial tion is practicable at all ordinary temperatures. The isobutene is here selectively absorbed, leaving the butene-l and butene-2 and other gases, if any, which are then conducted through sulphuric acid of a concentration of 80%,-more or less, by which the butene-1 and butene-2 are substantially absorbed. One of the advantages of this procedure arises from having removed the subn stances reactin to tertiary compounds since the reaction o the secondary-alcohol-forming substances with stronger acid for their conversion evolves heat of lesser degree, and the natural rise of temperature, for example to 40 C., may be permitted to take place, unless acid more concentracted than 80% is resorted to, in which case it may be desirable to hold the temperature down to a point below 15 C. These reactions are preferably carried out in a tower similar to the tower just mentioned; one tower may be used if arrangement is made to collect the gaseous efflux and repass it, supplying the more concentrated acid on the second passage and separately collecting the liquid efiiux from the first and the second passage.

The liquid from the first of said steps contains isobutene either absorbed in the acid or in the form of tertiary butyl alcohol by auto-hydrolysis in the dilute acid; this may be further diluted for complete hydrolysis and the alcohol distilled therefrom. Preferably the dilute liquid is neutralized with an alkali before distillation, to result in a much higher yield of the tertiary butyl alcohol by avoidance of reaction with the acidl during distillation.

The liquid from the second step of treatment contains the butene-l and butene--2, and this liquid may be diluted for complete hydrolysis into the secondary butyl alcohol, and thereafter distilled without neutralization to obtain a hi h yield of secondary butyl alcohol. The istillate may be dehydrated, if desired, by any usual or customary water-absorbent chemical treatment, such as treatment with lime or caustic.

The am lene fraction (3) whether collected by a sorption as described or'by pres- 85 sure condensation and fractional distillation (1) (propylene, ethylene, etc.) consists preponderantly of the amylenes and ma contain hexylenes and hi her olefines as, we l as h drocarbons of t e grou CH, This iquid mixture, which typically contains less than 5% of paralins, may advantageously be distilled into three parts corresponding to temperatures:-

(a) Up to 25 C. (b) 25 to 45 C. (c) Above 45 C.

Since the lower or more volatile olefines have been substantially removed as above described, distillate (a) consists primarily of iso-propyl ethylene, distillate (b) of pentene-l, pentene-2, unsymmetrical methylethyl-ethylene, and tri-methyl ethylene, and distillate (c) contains the hexylenes and heavier or higher boiling olefines.

The amylene fraction (3) can be treated with sulfuric acid in stages, or the fractions a) and (b) can be processed separately and with some advantage.

Distillate (a) contains predominant quantities of iso-propyl ethylene. The specific treatment of this distillate forms no part of our invention herein claimed.

In order to secure substantial yields of all alcohol derivatives from the mixed amylenes of fraction (b) it is desirable to remove the hydrocarbons of the group CH2 2 (and any still less saturated hydrocarbons) which may be present. Either of alternative processes is satisfactory at this stage.

It has been found, for example, that by.

treating this fraction first with concentrated hydrochloric acid, the amylenes which are convertible into tertiary derivatives are a substantially converted into chlorides which, owing to their relatively high boiling points,

can be easilv separated from the unchanged amylenes. he resulting mixture of chlorides on hydrolysis, carried on preferably with the addition of lime or caustic soda, yields tertiary alcohols.

We do not herein claim the s ecific method of recovery with the aid of ydrochloric acid treatment.

Alternatively the amylene fraction 3) ofV bons of a lesser degree of staturatlon than the olefines into heavy, oil-like polymers which, on account of diversity of boiling points, may be separated by fractional distillation, or other appropriate means, from the unchanged olefines.-

As the result of this preliminary reaction, for example either the said h drochloric or sulfuric acid treatments, a hlghly refined amylene fraction remains after treatment, which fraction is substantially a mixture of isopropyl ethylene, pentene-l and pentene-2, and which does not contain appreciable amounts of the other olefines, though there is no disadvantage in the presence of substantial amounts of the normal butylenes and hexylenes at this stage, since these olefines are of the same order of activity as the amylenes therein present, and their derivatives can easily be separated from those of the amylenes by fractional distillation.

Addition of sulfuric acid of a concentration of 77 more or less to this refined amylene causes absorption with concurrent formation of the corresponding intermediates of the alcohols from which the corresponding alcohols may be recovered by dilution and distillation.

To further illustrate the advantages of this invention we have treated the rich gas from vapor phase cracking as described, without first removing the amylene fraction, with 95% acid. The result was an evolution of excessive heat, rendering control difficult, if not impossible, and the recovery of small amounts only of secondary alcohols, and no tertiary alcohols. There were also formed large quantities of heavy tar-like pol mers. By first removing the olefines higlier than propylene we have successfully used fuming sulfuric acid as an absorbent for the remainder, obtained an/alcohol yield of 40% of the weight of acid used, and minimized the polymer formation to under of the alcohol produced.

For specific examples of treatment of the amylene fraction 3, (b) we have obtained the following results:

Ewa/mille I under conditions of thorough agitation keeping the mixture preferably below 420 C., and continue this treatment over a period of 6 hours as a maximum, adding the acid in two equal portions at 3 hour intervals. At the end of this `period .agitation is stopped and the mixture allowed to settle for a time sufficient to result in separation into two well-defined layers. We first draw off the lower or acid layer, which is carefully neutralized with caustic and distilled,

preferably through a fractionating column, cutting when the temperature reaches 100 C. at the top of the column. Under these specific conditions we recovered in this example .28 gallons of crude tertiary alcohols per 2.6 gallons of amylene fraction treated.

The residual hydrocarbons from this treatment to recover tertiary alcohols are distilled through a fractionating column from a slightly alkaline mixture, and ythe distillate up to C. is segregated and tlalrelated for conversion into secondary alco- Starting with 2.6 gallons of amylene fraction, there is recovered 1.1 gallons of hydrocarbons boiling up to 60 C. which are now treated with 77 HZSO.l in two portions, each of .55 gallons or 7.65 lbs. In this sta e the temperature is allowed to rise to 35 and maintained at under 40 C. preferably, and agitation is continued over a total period of six hours. The mixture is then allowed to settle and the lower or acid layer is drawn off, diluted with water 'to brm the concentration of acid below 20%, and then distilled until practically all of the alcohol is carried over. The distillate consists of two layers, a lower or water layer and an upper or alcohol layer. From the 2.6 gallons of amylene fraction at the start of this processing, there is recovered under the above specific conditions .56 gallonsof crude secondary alcohols.

`Secondary and tertiary butyl alcohols are successfully recovered from the butylene fraction by first scrubbing with more or less sulfuric acid, and then with 77% more or less sulfuric acid, as above described.

Example II The butylene fraction is first scrubbed or I treated lwith a relatively dilute sulfuric acid, followed by more concentrated acid. We have obtained satisfactory results by using in the first absorption stage 65% acid and in the second 77% acid. The amount of acid required depends upon the physical efliciencyof the absorption apparatus employed 1n large measure; using even comparatively ineflicient apparatus an acid efficiency can be. realized wherein three pounds of acid (calculated as 93%) produces-one pound of alcohol. From the treatment of 100 cu. ft. of the butylene fraction herein described, we

have produced .28 gallons of tertiary and .46 gallons of secondary alcohols.

During the absorption of the butylene in the treatment for tertiary alcohol with the particular reagents mentioned above we prefer to keep the temperature below 20 C., and during the secondary stage at about 35 C. As in the case of the tertiary amyl alcohol, it is necessary to distill the tertiary butyl alcohol from a neutral or slightly-alkaline solution to secure the highest yields, though tertiary butyl is not subject to decomposition in acid distillation in the saine degree as tertiary amyl alcohol.

lVherever in this specification particular concentrations of acid reagent substances adapted to olefine absorption are alluded to, it will be understood according to the common knowledge of the numerous chemists familiar with the. behavior of acids toward olenes for nearly a century, that the acid concentration is relative to the respectively mentioned or to normal temperatures, and that at different temperatures another concentration of acid is equivalent, within those limits at which the action of theacid reagent ceases to become an absorption, and enters upon the destructive formation of the compounds herein alluded to as polymers.

For the operations of fractional treatment with H2SO4 e. g. of the amylene fraction (b), we recommend the use of apparatus comprising a chamber adapted to be heated or cooled, and equipped for mechanical agitation of its contents; adapted for the slow feed of acid of the appropriate concentration; suitable settling vessels for decanting 0H the unchanged residue of the materials of lesser reactivity; and appropriate vessels for acid reaction upon the decanted residue. Distillation of the olefine-acid liquors `may proceed in appropriate steam stills. In essentials, the units of apparatus required are familiar in the practice of the chemical industries, and one of t-he advantages of this invention resides in the relatively simple nature of the instruments and operations required.

We claim:

1. In the process of generating secondary alcohols of 4 and 5 carbon atoms to the molecule from a mixture of hydrocarbons produced by cracking petroleum oil and containing olefines, the steps of separating from said mixture by distillation a fraction, the olefine content of which consists predominantly of secondary and tertiary olefines of the same number of carbon atoms to the molecule corresponding to the alcohol to be produced, selectively removing tertiary olenes from said fraction, and thereafter sulphating the secondary oleines contained in said fraction by admixing said fraction with aqueous sulphuric acid while maintaining an acid concentration and a. temperature at which sulphation of said secondary olefnes takes place.

2. Process according to claim l, in which the selective removal oftertiary olenes from said fraction is accomplished by admixing said fraction with aqueous sulphuric acid of from 60 to 65%, HzSO4 content, While maintaining a temperature below that at which substantial amounts of said secondary olefines are sulphated.

3. Process according to claim 1, in which the selective removal of tertiary olefines from said fraction is accomplished by admixing said fraction with aqueous sulphuric acid of from 6() to 65%, HZSO.,t content, at temperatures not exceeding 20 C.

4. In the process of generating secondary alcohols 0f 4 and 5 carbon atoms to the molecule from a mixture of hydrocarbons produced by cracking petroleum oil and containing not less than 30% of unsaturated hydrocarbons, the steps of separating from said mixture by distillation a fraction, the oleline content of which consists predominantly of secondary and tertiary oletines of the same number of carbon atoms to the molecule corresponding to the alcohol to be produced, selectively removing tertiary' olciines from said fraction, and-thereafter sulphating the secondary olefines contained in said fraction by admixing said fraction with aqueous sulphuric acid while maintaining an acid concentration and a temperature at which sulphation of said secondary olefines takes place.

5. Process according to claim 4, in which the selective removal of tertiary olefines from said fraction is accomplished by admixing said fraction with aqueous sulphuric acid of from 60 to 65%` H2504 content` while maintaining a temperature below that at which substantial amounts of said secondary oleines are sulphated.

6. Process according to claim 4, in which the selective removal of tertiary oletines from said fraction is accomplished by admixing said fraction with aqueous sulphuric acid of from 60 to 65%. HES()4 content, at temperatures not exceeding 20 C.

7. In the process of generating secondary butyl alcohol from a mixture of hydrocarbons produced by cracking petroleum oil and containing oletines. the steps of separating from said mixture by distillation a fraction, the oletine content of which consists predominantly of secondary and tertiary olefines of 4 carbon atoms to the molecule, selectively removing tertiary olefines from said fraction, and thereafter sulphating the secondary oleiines contained in said fraction by admixing said fraction with aqueous sulphuric acid while maintaining an acid concentration and a temperature at which sulphation of said secondary olefines takes place.

8. Process according to claim 7, in which the selective removal of tertiary olenes from said fraction is accomplished by admixing said fraction with a ueous sulphuric acid of from' 60 to 65%, H2 O4 content, while maintaining a temperature below that at which substantial amounts of said secondary olefines are sulphated.

9. Process accordin to'claim 7, invwhich the selective removal o tertiary olefnes from said fraction is accomplished by admixing isaid fraction with aqueous sulphuric acid of :from 60 to 65%, H2804 content, at temperatures not exceeding 20 C.

10. In the process of generating secondary butyl alcohol from a mixture of hydrocarbons produced by cracking petroleum oil and containing not less than 30% of olefines, the steps of separating from said mixture bydistillation a fraction, the olefne content of which consists redominantly of secondary and tertiary ole nes of 4 carbon atoms to the molecule, selectively removing tertiary olefnes from said fraction, and thereafter sulphating the secondary olenes contained in said fraction by admixing said fraction with aqueous sulphuric acid while maintaining an acid concentration and a temperature at which sulphation of said secondary olefines takes place.

11. Process according to -claim 10, in which the selective removal of tertiary olefines from said fraction is accomplished by admixing said fraction with aqueous sulphuric acid of from 60 to 65%, H2SO4content, while maintaining a temperature below that at which substantial amounts of said secondary olefines are sulphated.

12. lProcess according .to claim 10, in which the selective removal of tertiary olefines from said fraction is accomplished by admixin said fraction with a ueous sulphuric acid o from 60` to 65%, Hzg tures not exceedin -20 C.

Signed by us at ambridge, Massachusetts, this nineteenth day of Februa 1925.

` HAROLD S. D VIS. c WALLACE J. MURRAY.

04 content, at tempera? 

